The Children's Hospital of Philadelphia has contributed to the science of the Childrens Cancer Group in the last 25 years with regard to patient entry on study, scientific leadership in committees and strategy groups, and the initiation and performance of pilot studies. Specific contributions have been the following: 1) Use of bone marrow transplant following high dose intensive therapy for neuroblastoma; 2) Development of clinical and biology studies in neuro-oncology that will be incorporated into randomized Group trials; 3) Initiation of a method of performing epidemiologic studies utilizing the random-digit dialing technique in Group studies of retinoblastoma, brain tumors and parental occupation through funded grants; 4) Providing leadership and expertise in developing studies of late effects of cancer therapy; and 5) Performing studies for leukemia, Hodgkin's disease, lymphomas, rhabdomyosarcoma, and brain tumors serving as early pilots for the Group. The investigators participating in this endeavor will continue to provide data of high quality for patients entered on study as well as leadership in the areas of basic science, late effects of therapy, neuro-oncology, bone marrow transplantation, biologic response modifiers and etiology and prevention. More than 100 patients have been entered on CCG studies annually from CHOP and its affiliates -- the Wilmington Medical Center, Geisinger Medical Center and Albert Einstein Hospital, and more than 1,000 are being followed on study; it is expected that this number will increase in the future as studies for diseases not now available are initiated. CHOP investigators now chair major Strategy Groups (ANL, Lymphoma and Soft Tissue Sarcoma) and are providing committee leadership in all areas of study. There are 23 investigators in this institution holding 108 positions on study committees, strategy groups, or scientific committees, 20 of them being in positions of leadership. We will continue to enroll all eligible patients and to conform to group requirements with regard to study participation, in addition to providing leadership in the specific areas noted above.